On Jul 30 11:25:23, Stuart Henderson wrote:
> >> it was even async, which makes me curious about the install slowness.
> >> Could the card or the exact mount options be the cause of that?
>
> Well, you already noticed the main difference; one is async, the
> other uses softdep. That should suggest a simple test you can make;
> untarring on a running system with async vs softdep...
Here's what I just did:
- downloaded xserv45.tgz onto /home
- (re)mounted /tmp with 'async' or 'softdep' respectively
- cd /tmp ; time tar xzf /home/hans/xserv45.tgz
- rm -rf what came out of it ; umount /tmp
- repeat several times, toggling the mount option
(I am using /tmp because that's the only filesystem
whose options I can fool around with now; and my /tmp
is 128M, that's why I use xserv45.tgz and not base45.tgz;
and it should have been tar xzpf I guess - does it make
a difference? And it shloud be done in single user - but
the machine is almost idle, really.)
With async, the untar took anywhere between 1:25 and 1:40.
With softdep, the untar took anywhere between 1:16 and 1:36.
So they are not that much different, and neither of them shows
the ultraslow behaviour I was experiencing during the install.
What else could it be?
For some reason (no reason), I have always thought that nothing can
be faster than async. What is the rationale for mounting the target
filesystems async mounts during an install, anyway?
> I have a feeling softdep may be faster in this case, but it has
^^^^^^^^^^^^
> drawbacks too.
Meaning, a slow IO?
What's specific about async vs. softdep in this case?
> > I suppose you use an CF-card with about x133 speed. I had the same problem.
> > After using a card with at least x233 speed I didn't have that problem when
> > untaring anymore.
If buying a 'faster' card solves my problem, so be it.
But I would like to know, anyway.
> The speed rating by itself isn't very useful. The random-access write
> speed has the biggest effect when used on a computer and since it is
> hardly relevant to use with a camera, doesn't usually get mentioned.
This confuses me: isn't the write speed very relevant when
making shots in quick succession, for example? Or is it that
the write speed is high enough for any camera, and therefore not
relevant in a camera, as opposed to computer use, where data could
be generated much more quickly?
> In particular look for cards which do multisector transfers (i.e.
> they /don't/ say "1-sector PIO" in the attach line in dmesg), e.g.
> almost all recent sandisk, some innodisk cards, and not many others.
Thanks for the tip.
$ grep 'sector PIO' dmesg/*
dmesg/alix1c:wd0: 1-sector PIO, LBA, 3847MB, 7880544 sectors
dmesg/alix2c1:wd0: 1-sector PIO, LBA, 3871MB, 7928928 sectors
dmesg/alz:wd0: 16-sector PIO, LBA, 19092MB, 39102336 sectors
dmesg/armada:wd0: 16-sector PIO, LBA, 14403MB, 29498112 sectors
dmesg/fjfi:wd0: 16-sector PIO, LBA48, 239371MB, 490232639 sectors
dmesg/gw:wd0: 1-sector PIO, LBA, 3871MB, 7928928 sectors
dmesg/vlada:wd0: 16-sector PIO, LBA, 38166MB, 78165360 sectors
dmesg/vlada:wd1: 16-sector PIO, LBA, 78167MB, 160086528 sectors
dmesg/wind:wd0: 1-sector PIO, LBA, 7647MB, 15662304 sectors
dmesg/wind:wd1: 16-sector PIO, LBA48, 476940MB, 976773168 sectors
dmesg/www:wd0: 1-sector PIO, LBA, 3847MB, 7880544 sectors
Damn.
Seems all of my CF cards are '1-sector PIO'
(and all of my hard disks use '16-sector PIO').
> Also on the Alix systems note that there's a UDMA option you can
> enable in tinyBIOS that defaults to Off.
I don't remember whether I set this, but
wd0 at pciide0 channel 0 drive 0: <ELITE PRO CF CARD 4GB>
wd0: 1-sector PIO, LBA, 3847MB, 7880544 sectors
wd0(pciide0:0:0): using PIO mode 4, Ultra-DMA mode 2
makes me think I have DMA enabled.
Thanks for your time
Jan
